| Cause | Appearance | Description |
| Tuberculosis | ||
| Pyoderma gangrenosum | |
|
| Syphillis |
|
|
| Arteriovenous fistulae |
|
|
| Rheumatoid arthritis |
|
|
| Squamous cell carcinoma |
|
|
| Sickle cell disease |
|
| Cause | Appearance | Description |
| Tuberculosis | ||
| Pyoderma gangrenosum | |
|
| Syphillis |
|
|
| Arteriovenous fistulae |
|
|
| Rheumatoid arthritis |
|
|
| Squamous cell carcinoma |
|
|
| Sickle cell disease |
|